Leather shaving machine



April 1964 A. H. HORN ETAL LEATHER SHAVING MACHINE BLADE SPACING NOT TOEXCEED L25" 'QMMW Ari/5212' .Efivrzz girl) W300! Filed April 20, 1962 indates This invention relates to leather shaving machines in which arapidly rotating cylinder with helical blades thereon pitched inopposite directions from the center of the cylinder toward the endsthereof, performs a cutting or shaving operation upon leather as it isdrawn into the machine under the control of the operator. Since thelength of the cutting cylinder determines the maximum width of the pieceof leather that can be acted upon at one time, it seems but logical thatleather shaving machines would be made with cutting cylinders longenough to accommodate the full width of a side of leather, especiallysince it is obviously advantageous from a production cost standpoint tobe able to shave a full width of a side of leather With each passthrough the machine.

A side of leather is half a tanned hide. Cow hides are almost always outin two, right down the back bone. Only where unusually large pieces ofleather are required, as for table tops, is a cow hide tanned andfinished in one piece. Thus tanners think in terms of sides.

To appreciate this invention and fully understand its place andsignificance to the tanning industry it should also be understood thatthe shaving operation is performed on the tanned leather (usually chrometanned) and not the fresh hide; and that the tanned leather is in a wetlimp state when it is shaved. Another fact to be borne in mind is thatshaving is performed only after the side of the leather has been split.Generally speaking, only sides (or leather) that are intended for use assole leather are not split.

Splitting is done on machines such as that of the Meyer Patent No.1,410,703. By this operation the side of leather is split into at leasttwo and sometimes more pieces, at least one of which is substantiallyuniform in thickness, and since the first split is made with the grainside of the leather against the gage roll, the largest piece obtained isalways of the first quality and is the one of substantially uniformthickness. Although the split sides are fairly uniform in thickness thesplitting knife does not leave too smooth a surface, so that for use asupper leather this surface must be shaved. Also for this purpose thethickness of the leather must be as close as possible to uniform.

Despite the obvious advantages of performing the shaving operationacross the full width of a side, leather shaving machines heretoforeavailable have not had this capacity. An the contrary, the cuttingcylinders of shaving machines used by the industry for years have notbeen much longer than twenty-four inches, which is not even half thelength needed to act upon the full width of a side of leather at onetime. This severe limitation upon the capacity of leather shavingmachines is all the more significant in view of the fact that leathershaving machines have been available for many years, as evidenced, forinstance, by the Taylor Patent No. 277,631, issued in 1883.

The lack of leather Working machines with cutting cylinders long enougto act upon the full width of a side of leather was not due to anyinability on the part of the manufacturers of leather working machineryto produce longer helically bladed cutting cylinders. They have beendoing this for a long time. The difliculty lay in the fact that withprior shaving machines the operator of the machine could not properlycontrol the entry of the ate J p 3,129,578 Patented Apr. 21, 1964 sideof leather into the machine if much more than twenty-four inches ofcylinder length acted thereon at one time. The pull exerted upon theside by a twentyfour inch cylinder length was about the limit that anoperator could successfully resist and control.

Since sides of leather are much wider than twentyfour inches, theoperator had to perform a minimum of four shaving operations on eachside. In other Words, he had to feed the side into the machine at leastfour different times.

The time required for these four shaving operations, plus the fact thatconsiderable skill is required to properly operate a leather shavingmachine, made the leather shaving operation a significantly expensivepart of the tanning and leather finishing process. The seriousness ofthis situation has been recognized by the industry for many years.Nevertheless, no one heretofore has been able to solve the problem thatkept the attainment of the desired objective from being realized. Thisinvention solves that problem.

To appreciate the problem and its solution, it must be understood that,in leather shaving, it is important that all portions of the sideandparticularly the shank and foreleg portions thereofare straightened andsmoothed out onto the feed and backup roll before the cutting cylindercontacts it. If this is not done, these peninsular-like portions of theside will be completely or partially cut off, which of course wouldresult in an economic waste. Accordingly, the shaving machine must be sodesigned and constructed that the operator has a full View of the sideas it is fed into the machine, and the machine must feed or draw theside into it, not out of it.

But, most important, the operator must have control over the side at alltimes, despite the fact that once the side is gripped between thecutting cylinder and the feed and backup roll, the rapidly revolvingcutting cylinder exerts a substantial pull upon the side. Since the pullthus exerted upon the side, per unit of length of the cutting cylinder,was such that an operator could not successfully cope with much morethan that produced by twentyfour inches of cutting cylinder action, andsince the art did not known how to reduce this pull factor withoutgetting into such problems as chattering and uneven shaving, thelimitation was generally accepted as inevitable.

The problem to which this invention is addressed namely, that ofincreasing the capacity of leather shaving machines-was recognized bythe patentee Blaney in his Patent No. 1,621,577, issued March 22, 1927;and While Blaney offers a solution to the problem, his machine has thedisadvantage of receiving the side (which he calls a skin) to beinserted into the machine in such a way that the operator has no controlover the side and cannot see it as it approaches the cutting cylinder.Blaney sought to solve the problem by substituting mechanical means formanual control, which has never been practicable in leather shaving. Inpresenting his invention, the patentee observes:

In shaving machines, as heretofore constructed, the cutting cylinder hasordinarily been of such a dimension as to present an effective cuttingsurface approximately twelve inches in length, although more recentlylarger cylinders have been employed with an effective cutting surface ofabout two feet in length. In operating with either machine, it isnecessary for the operator to shave a portion of a skin and to shift theskin repeatedly in both lateral and longitudinal directions to operateupon adjacent portions, the Whole operation of shaving a skin requiringthe greatest skill in order to obtain uniformity throughout all portionsof the shaved skin and to avoid the presence of ridges or scores orother lines of demarcation between adjacent areas successively operatedupon. Moreover, the shaving of perforated portions of the skin and ofthe margins, and especially of those parts which form projections ortabs extending from the body portions, make great demands upon the skilland patience of the operator. It is not surprising, therefore, thatoperators on shaving machines are among the most highly paid employeesof leather manufacturing plants.

It is an object of this invention to provide a shaving machine ofrelatively great capacity, when compared with prior machines, which maybe operated satisfactorily by the ordinary workman without the exereciseof expert knowledge.

Although the Blaney patent discloses a leather shaving machine largeenough to operate upon an entire side at one time, it achieved itspurpose at the expense of foregoing the accepted and proven method ofoperating shaving machines. For successful leather shaving, the sidemust be fed into the machine and not out of the machine. Otherwise theoperator can not maintain the required control over the side as theshaving operation begins and while it is in progress. Hence, the machineof the Blaney patent is no answer to the problem which has confrontedthe art ever since leather shaving machines were first produced.

The discovery which led to the invention has made it possible forleather shaving machines large enough to accept and openate upon anentire side at one time, to be successfully operated by a singleoperator, Without in anywise increasing the amount of pull that he hasto exert upon the side in controlling it, as it is fed into themachine-or, in fact, as the shaving operation proceeds. This discoveryis simply that the angle and spacing of the helical blades of thecutting cylinder is ciritical, and must be maintained between definitelimits.

Although the invention could probably be described without recourse todrawings, since basically the leather shaving machine of this inventiondoes not depart from past practice, except in the critical areas abovereferred to, it will no doubt be helpful to refer to the accompanyingdrawing, in which:

FIGURE 1 is a side view of the main portion of a leather shaving machineof this invention; and

FIGURE 2 is a front elevational view of a central portion of the cuttingcylinder of the machine.

On this drawing, the numeral 5 designates the cutting cylinder of themachine and the numeral 6 indicates the combined feed and backup rollwhich holds the side against the cutting cylinder during the shavingoperation and which has a solid unyielding work engaging surface.

The cylinder 5, as in all prior leather shaving machines, has helicalblades 7 on its periphery, which are pitched in opposite directions fromthe center of the cylinder, so that as the cylinder acts upon the side,these blades spread the side out toward the ends of the cylinder anoperation customarily known as putting out."

The cylinder 5 is journalled in bearings 8, which are mounted in the endframes 9 of the machine, only a portion of one of which is shown inFIGURE 1; and any suitable means is provided for revolving the cylinderin a clockwise direction, as viewed in FIGURE 1, and at relatively highspeed. For purposes of illustration, the means for driving the cylinderis shown as a belt 19 trained over a pulley 1-1 which is fixed to theadjacent end of the cylinder shaft. In practice, the cutting cylinderrevolves at a speed of between 1750 and 2000 r.p.m.

The edges of the helical blades are kept sharp by a grinding wheel 12which is mounted on the frame of the machine and which, in operation,travels back and forth along the length of the cutting cylinder.

The combined feed and backup roll 6 is journalled in a swinging framestructure, indicated generally by the numeral 13, for movement towardand from the periphery of the cutting cylinder. The frame structure 13is pivoted, as at 14, between portions 15 of the end frames 9. Anysuitable means may be supplied to swing the frame 13 about its pivotalmounting between closed and open posi- 4 tions. In the closed positionthe feed and backup roll is directly contiguous to but spaced atdefinite adjustable distance from the cylinder, holding the hide orother Work H against the blades of the cylinder. In the open position,the combined feed and backup roll is spaced approximately one inch fromthe periphery of the cutting cylinder.

The swinging frame 13 also mounts a roll 16 which is disposed forwardlyof the feed and backup roll, i.e. towards the operator, and spanning thedistance between the upper peripheral portions of the rolls 6 and 16,with its top surface substantially tangent to these rolls, is a transfertable 17. Another table 18 projects forwardly from the roll 16, uponwhich the operator may place the side preparatory to feeding it into themachine.

The rolls 6 and 7 are power driven by means of a chain 19 trained over adrive sprocket 20 which rotates about the pivot axis 14, and oversprockets 21 and 22, respectively fixed with respect to the rolls 6 and16. The drive sprocket 20 is driven from a power source in any suitablemanner, as by means of a belt 23 trained over a pulley fixed withrespect to the drive sprocket 20.

The peripheral speed of the rolls 6 and 16 is in the neighborhood of 40rpm. which, of course, is greatly less than the peripheral speed of thecutting cylinder; and since it is desired that the side of leather orother work being acted upon move into the machine and past the cuttingcylinder at the peripheral rate of the feed and backup roll, the surfaceof this roll is roughened to give it a better grip upon the hide. Sincethe roll 6 is generally formed of steel, sand blasting its surfaceprovides the desired roughening.

As noted hereinbefore, it has been discovered that if the angle of thehelical blades, i.e. the angle at which these blades are disposed withrespect to a plane normal to the axis of the cylinder-as shown at inFIGURE 2- is maintained at 22 plus or minus 3, and if the spacingbetween adjacent helical blades does not exceed 1.25 inches, the pullwhich a cutting cylinder fifty inches long exerts upon the side ofleather being acted upon by the full length of the rapidly revolvingcylinder, is no greater than that which in the past was exerted upon theside by a cutting cylinder less than 24 inches in length. Therefore,with the helical blades of the cutting cylinder disposed in accordancewith this invention, a single operator can easily and successfullyoperate the shaving machine, despite the fact that its cutting cylinderand rolls are 50 long, which is long enough to accommodate a full widthof a side of leather.

The minimum spacing between adjacent blades is limited by practicalconsiderations, notably the fastening of the blades to the cylinder, andordinarily cannot be less than one inch.

In operating the machine of this invention, the operator carefullyspreads the leading portion of the side over the table 17 and then overthe surface of the feed and backup roll 6, making sure that theprojecting end portions, Whether they be shank or fore legs, are spreadsmoothly across the roll 6 before the blades of the cutting cylindercome into contact therewith. Then, as the side is drawn into the machineby the coacting cutting cylinder and feed roll, the operator watchesthat no portion of the side will be doubled up or folded and, ingeneral, makes certain that proper feeding takes place.

Since the pull which the machine exerts upon the side of leather doesnot exceed the pull which the operator can himself exert upon the side,he can, of course, withdraw the same from the machine and restart theshaving operation if necessary. The important thing, however, is that atall times the operator has absolute control over the hide to thus assuresatisfactory shaving, and further that because the cutting cylinder islong enough to accept the full width of a side, only two passes arerequired, whereas previously a minimum of four was necessary.

The criticality of the angle and spacing of the helical cutting bladesset forth herein has been verified by actual use of machines made inaccordance with this invention, by experienced shaving machine operatorsin actual commercial use.

What is claimed as our invention is:

1. In a leather shaving machine having a cutting cylinder with helicalblades thereon pitched in opposite directions from the center of thecylinder towards the ends thereof, a backup member having a solidunyielding Work engaging surface to hold the portion of a side ofleather being acted upon against the blades of the cutting cylinder, andmeans to rapidly revolve the cutting cylinder in the direction to draw aside of leather placed between the cylinder and the backup member intothe machine and at the same time spread the side out towards the ends ofthe cylinder, the cylinder and the backup member being separable toallow a side of leather to be removed from the machine after the shavingoperation, the improvement which enables the cutting cylinder to be longenough to accommodate the full width of a side and to act thereonwithout applying more tension upon the side than an operator can readilyresist and control, and which improvement comprises the followingcritical angle and spacing of the blades and cutting cylinder:

(A) the angle which the blades form to a plane normal to the axis of thecylinder, is 22 plus or minus 3; and

(B) the spacing between adjacent blades does not exceed 1.25 inches, andis not greatly less than one inch.

2. In a leather shaving machine having a cutting cylinder with helicalblades thereon pitched in opposite directions from the center of thecylinder towards the ends thereof, a combined backup and feed rollhaving a solid unyielding work contacting surface to hold the portion ofa side of leather being acted upon against the blades and feed the sameinto the machine, and

means to revolve the cutting cylinder and backup and feed roll inopposite directions of rotation, with the backup and feed rolltravelling at a periperal speed much slower than that of the cuttingcylinder, and with the directions of rotation such that a side ofleather gripped between the cylinder and backup and feed roll will bedrawn into the machine, said machine being characterized by thefollowing:

(A) The angle which the blades of the cutting cylinder form to a planenormal to its axis is 22 plus or minus 3; and

(B) the spacing between adjacent blades does not exceed 1.25 inches, andis not greatly less than one inch,

so that the pull exerted on the side of leather by the rapidly revolvingcutting cylinder as the cylinder performs its shaving and spreadingfunctions is not so great than an operator cannot easily control theentry of the side into the machine, despite the fact that the cuttingcylinder and backup and feed rolls are long enough to accommodate thefull width of a side of leather.

3. The leather shaving machine of claim 2, further characterized by thefact that the combined backup and feed roll has its surface roughened.

References Cited in the file of this patent UNITED STATES PATENTS277,631 Taylor May 15, 1883 526,387 Evans Sept. 25, 1894 638,368 WaylandDec. 5, 1899 999,540 Baker Aug. 1, 1911 1,183,758 OBrien May 16, 19161,410,703 Meyer Mar. 28, 1922 1,621,577 Blaney Mar. 22, 1927 1,863,777Wayland June 21, 1932 2,570,470 Meyer et al Oct. 9, 1951 2,674,114 Brillet a1. Apr. 6, 1954

1. IN A LEATHER SHAVING MACHINE HAVING A CUTTING CYLINDER WITH HELICALBLADES THEREON PITCHED IN OPPOSITE DIRECTIONS FROM THE CENTER OF THECYLINDER TOWARDS THE ENDS THEREOF, A BACKUP MEMBER HAVING A SOLIDUNYIELDING WORK ENGAGING SURFACE TO HOLD THE PORTION OF A SIDE OFLEATHER BEING "ACTED" UPON AGAINST THE BLADES OF THE CUTTING CYLINDER,AND MEANS TO RAPIDLY REVOLVE THE CUTTING CYLINDER IN THE DIRECTION TODRAW A SIDE OF LEATHER PLACED BETWEEN THE CYLINDER AND THE BACKUP MEMBERINTO THE MACHINE AND AT THE SAME TIME SPREAD THE SIDE OUT TOWARDS THEENDS OF THE CYLINDER, THE CYLINDER AND THE BACKUP MEMBER BEING SEPARABLETO ALLOW A SIDE OF LEATHER TO BE REMOVED FROM THE MACHINE AFTER THESHAVING OPERATION, THE IMPROVEMENT WHICH ENABLES THE CUTTING CYLINDER TOBE LONG ENOUGH TO ACCOMMODATE THE FULL WIDTH OF A SIDE AND TO ACTTHEREON WITHOUT APPLYING MORE TENSION UPON THE SIDE THAN AN OPERATOR CANREADILY RESIST AND CONTROL, AND WHICH IMPROVEMENT COMPRISES THEFOLLOWING CRITICAL ANGLE AND SPACING OF THE BLADES AND CUTTING CYLINDER:(A) THE ANGLE WHICH THE BLADES FORM TO A PLANE NORMAL TO THE AXIS OF THECYLINDER, IS 22* PLUS OR MINUS 3*; AND (B) THE SPACING BETWEEN ADJACENTBLADES DOES NOT EXCEED 1.25 INCHES, AND IS NOT GREATLY LESS THAN ONEINCH.